Göttingen 1997 – scientific programme
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HK: Hadronen und Kerne
HK 3: Schwerionenreaktionen, niedrige Energien
HK 3.7: Talk
Monday, March 24, 1997, 15:45–16:00, HS D
Dissipation and entropy production in coarse grained Vlasov equations — •K. Morawetz1, P. G. Reinhard2, and R. Walke1 — 1AG Quantentheorie und Vielteilchensysteme, FB Physik Universität Rostock, Universitätsplatz 3, D-18051 Rostock — 2Institut für theoretische Physik, Universität Erlangen, Staudtstrasse7, D-91058 Erlangen
The Vlasov equation is analyzed for the coarse graining which is involved in numerical solutions using the test particle method. The finite width of the test particles folds the distribution which obeys now a Vlasov equation with an additional term. The latter one can be considered as a source for entropy production and dissipation. This is the one-body dissipation as observed in [1] in the limit of infinite number of test particles. We demonstrate in a simple model [2] that there are two mechanisms for this dissipation: (i) The folding averages over neighboured energy shells with different orbital frequencies Ω(E). This is already active for the case of a fixed external field. (ii) Nonlinear recoupling in case of a selfconsistent field generates energy flow across the single-particle energy shells. The mechanism (i) gives the more general class of stationary states whereas (ii) leaves essentially Boltzmann equilibrium states. Finally, we investigate the consequences of the folding on the dynamical response function.
[1] E. Suraud, P.-G. Reinhard, Ann.Phys. (N.Y.) 239 (1995) 193,216
[2] K. Morawetz and P. G. Reinhard, Phys. Lett. B. (1996), sub.